Looking for Domain and Range using a Graph - For: Maria Andrea Guillen

One of the easiest ways of solving for the domain and range of a function is by looking at its graph. The domain would be the span of the X values; and the range, the span of the Y values. However, you must be careful since the graph will not cover all numbers until infinity, so you also have to apply some logic. For instance,

Take a look at the graph of f(x)=2^x

Domain: The domain will be all real numbers since every x-value has a y-value, or the function passes through every x-value. Even though, in the graph, the red line does not go beyond x=2.25, you should be able to tell that the domain goes beyond that by picturing a graph that covers more values. If you're not sure about this, you can always graph the function in your graphing calculator and zoom out as much as you want.

Range: The range is only all positive numbers. f(x) never equals a negative value for y. You can see it on the graph. The function never passes through a negative y-value. It never goes below the x-axis, and it never touches zero.